Related Articles

The blind, furless creatures that live underground in colonies lack a body chemical called Substance P, a neurotransmitter normally in the skin that sends pain signals to the central nervous system. The rats feel no immediate pain when cut, scraped or subjected to heat stimuli. They only feel some aches. But when the rats get a shot of Substance P, pain signaling resumes working as in other mammals.

"It was a complete surprise when we discovered that the skin of naked mole-rats is missing one of the most basic chemicals that's found in the skin of all other mammals," said Thomas Park, associate professor of biological sciences at the University of Illinois at Chicago and the principal investigator in the research project.

Co-investigators include Christopher Comer, professor of biological sciences, Ying Lu, assistant professor of anesthesiology and Charles Laurito, professor of anesthesiology -- all at UIC -- along with pharmacologists Frank Rice of the Albany Medical College in Albany, N.Y. and Steven Wilson, of the University of South Carolina School of Medicine.

The findings were reported in a presentation by Lu Nov.8 in New Orleans at the annual meeting of the Society for Neuroscience.

Some medical researchers believe an excess of Substance P causes the human condition fibromyalgia, where patients suffer from chronic pain in soft fibrous body tissue such as muscles, ligaments and tendons. Theoretically, reducing or eliminating Substance P in affected areas could ease the pain. Experiments using naked mole-rats may help test this hypothesis and perhaps lead to new therapies.

"After we discovered that naked mole-rats naturally lacked Substance P, we realized that we had a unique situation whereby we could try to re-introduce this chemical to better understand its role in pain signaling," said Park.

A virus was applied to the feet of the rats to transport DNA that codes for Substance P through nerve endings on the skin. The virus then migrated over a period of a few days to nerve cells near the spinal cord where the DNA produced Substance P.

Each foot used was then anesthetized and held close to an uncomfortably warm -- but not damaging -- lamp to activate nerve fibers associated with Substance P but not other types of nerve fibers. The rats' feet treated with Substance P quickly recoiled. Those not treated also withdrew from the lamp, but much more slowly.

A key unanswered question is why naked mole-rats evolved over perhaps millions of years to have no Substance P in their skin and became oblivious to normal pain stimuli.

One possible explanation is that because these curious creatures have had to cope with high levels of carbon dioxide in their crowded underground tunnel colonies -- a condition that normally would cause the type of pain associated with Substance P in mucous membranes throughout the animals' bodies -- they have become insensitive to the pain.

Another possibility involves Substance P and blood vessel dilation in the skin -- to cool the body surface. In cold-blooded naked mole-rats, however, dilation would cause them to dangerously overheat, so they may have evolved to eliminate Substance P from their skin.

"We were surprised by how dramatic the results were," said Park. "We expected Substance P could restore some sensitivity to painful stimuli, but it was a real surprise that this single chemical could make the naked mole-rats behave just like other mammals."

Further experiments are planned with the rats to investigate how other pain systems work in the absence of Substance P.

Funding for the research was provided by grants from the National Institutes of Health.

More From ScienceDaily

More Health & Medicine News

Featured Research

Mar. 3, 2015 — Adults over the age of 30 only catch flu about twice a decade, a new study suggests. So, while it may feel like more, flu-like illness can be caused by many pathogens, making it difficult to assess ... full story

Mar. 3, 2015 — No significant change in home habits of smokers have been observed in the aftermath of a ban on smoking in public spaces, researchers report. Greater inspiration to kick the habit likely comes from ... full story

Mar. 3, 2015 — Heart function has been associated with the development of dementia and Alzheimer's disease through a new study. Participants with decreased heart function, measured by cardiac index, were two to ... full story

Mar. 3, 2015 — Children of recently separated or divorced families are likelier to drink sugar-sweetened beverages than children in families where the parents are married, putting them at higher risk for obesity ... full story

Mar. 3, 2015 — Gastric bypass and similar stomach-shrinking surgeries are a popular option for obese patients looking to lose weight or treat type 2 diabetes. While the surgeries have been linked to a decreased ... full story

Mar. 3, 2015 — Most people consume more salt than they need and therefore have a higher risk of heart disease and stroke, which are the two leading causes of death worldwide. But a new study reveals that dietary ... full story

Mar. 3, 2015 — Twice as many children born to mothers who took antibiotics during pregnancy were diagnosed with asthma by age 3 than children born to mothers who didn’t take prenatal antibiotics, a new study has ... full story

Mar. 3, 2015 — Pediatric otolaryngologists and surgeons are concerned with parents getting the wrong message regarding the safety/desirability of letting babies and young children eat peanuts to prevent them from ... full story

Featured Videos

Mom Triumphs Over Tragedy, Helps Other Families

AP (Mar. 3, 2015) — After her son, Dax, died from a rare form of leukemia, Julie Locke decided to give back to the doctors at St. Jude Children&apos;s Research Hospital who tried to save his life. She raised $1.6M to help other patients and their families. (March 3)
Video provided by AP

Looted and Leaking, South Sudan's Oil Wells Pose Health Risk

AFP (Mar. 3, 2015) — Thick black puddles and a looted, leaking ruin are all that remain of the Thar Jath oil treatment facility, once a crucial part of South Sudan&apos;s mainstay industry. Duration: 01:13
Video provided by AFP

Woman Convicted of Poisoning Son

AP (Mar. 3, 2015) — A woman who blogged for years about her son&apos;s constant health woes was convicted Monday of poisoning him to death by force-feeding heavy concentrations of sodium through his stomach tube. (March 3)
Video provided by AP

Related Stories

Aug. 29, 2014 — A factor in naked mole rat cells could be one of the secrets to how the rodent defies aging, researchers say. Naked mole rats, which burrow through underground tunnels in their native East Africa, ... full story

Aug. 19, 2014 — The naked mole rat, the longest lived of rodents, shows superior cardiovascular function to old age in two studies. Cardiovascular disease is the greatest killer of humans the world over, presenting ... full story

June 19, 2013 — Scientists have discovered the chemical that makes naked mole rats cancer-proof. Naked mole rats are small, hairless, subterranean rodents that have never been known to get cancer, despite having a ... full story

Sep. 21, 2012 — Naked mole-rats evolved to thrive in an acidic environment that other mammals, including humans, would find intolerable. Researchers report new findings as to how these rodents adapted, which may ... full story

Dec. 20, 2011 — Researchers have found out why the African naked mole-rat, one of the world's most unusual mammals, feels no pain when exposed to acid. The animals have an altered ion channel in their pain ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.